Most gas and oil wells today use either a positive displacement pump in which a pump or plunger is located within the delivery tube adjacent the bottom thereof, which tube is located within the well casing. The pump is moved by a pump rod which is connected to a walking beam located at ground level. Other types of wells will use the natural pressure in the well to force the fluid out of the well casing through the delivery tube and into a storage or sales line. Various controls have been devised for use with this latter type of well pumping or delivery system in which the pressure differential existing between the well casing and delivery tube is measured and upon reaching a predetermined differential amount will actuate the appropriate controls for opening the motor valve in the sales line. Opening of the motor valve will permit the natural pressure within the casing to force the fluid up and out of the delivery tube and into the sales line. Once actuated these wells will operate for a predetermined time period before shutting down automatically by a timer or the like. In other types the motor valve will shut down upon the pressure differential reaching a predetermined lower limit.
However, no such pressure differential sensing device has been used for controlling the pumping units of wells using a positive displacement pump. Heretofore, these positive displacement pump wells have used a mechanical timing device which actuates the well for a predetermined length of time at various time periods throughout the day. Another type uses a load sensing system in which a load cell is incorporated with the pump rod of the walking beam and monitors the lifting load on the rod in relationship to the plunger position. The load cell is connected to appropriate electronic controls for either maintaining the pumping unit energized or deenergizing the pumping unit upon certain load valves being obtained. These load cell control systems are relatively expensive and require installation of the cell in the pump rod and requires complex electronic circuitry for controlling the well from the signal received from the load cell.
Furthermore, existing timers that are used for controlling the pumping unit cannot adjust automatically for premature and/or successive pump off of fluids, and thus do not provide the most efficient utilization of the well.
There is no known controller of which I am aware that is used with a positive displacement pumping system for obtaining optimum pumping efficiency which uses the pressure differential existing between the pressure of the fluid in the well casing and in the delivery tube, in combination with the position of the walking beam for maintaining or deenergizing the pumping unit.